1. Field of the Invention
The present invention relates to a polyolefin resin composition suitable for use in the forming of flexible sheets, a foamed resin sheet manufactured therefrom, and a wall paper using such sheet. More specifically, the present invention is concerned with a resin composition having excellent roll processability and flexibility, a foamed resin sheet rollings manufactured therefrom, and a wall paper using such sheet.
2. Description of the Background
Wall papers have such structure that a foamed synthetic resin sheet is laminated onto one side of the paper substrate. Up to the present, sheets made of polyvinyl chloride resin have been used mainly for such foamed synthetic resin sheet. Polyvinyl chloride resin sheets have been evaluated highly and utilized because of their good moldability, fire-retardant property and excellent workability. However, there is a growing trend for polyvinyl chloride resin sheets to be gradually replaced by substitute materials on account of concerns about environmental problem due to their own combustion gases and the effects of the plasticizer contained in them on human health.
From a viewpoint of environmental and health concerns, polyolefin resins are safe materials involving little concerns about environmental problem and effects on health. On the other hand, it has been pointed out that polyolefin resins do not show satisfactory sheet formability on calendering rolls, exhibit a low expansion ratio in the processing of foaming, provide sheets having the surfaces giving a different feel from that of the conventional polyvinyl chloride sheets, and have disadvantages to be improved such as the laminates with paper tending to curl.
In this respect, the selection of an ethylene/.alpha.-olefin copolymer from among polyolefin resins allows foamed sheets having excellent flexibility and foamability to be obtained. However, as the resin does not feed well between the calendering rolls, the resin shows poor high-speed processability and has disadvantages to be improved such as formed sheets exhibiting a decline in the accuracy in their thickness.
On the other hand, the Japanese Laid Open Patent Publication No.17724/1998 discloses a wall paper using a sheet with excellent calendering roll processability and foamability which uses a particular ethylene/.alpha.-olefin copolymer. However, the sheet shows high impact resilience and difficulty in cutting because of its rubber elasticity and therefore does not always display satisfactory workability. It follows therefore that as things stand now, even if any type of polyolefin resin is selected, sheets having excellent moldability and physical properties cannot be obtained.